Fluid-break switch



July 20,1926. 1,593,405

v J. D. HILLIARD FLUID BREAK SWITCH Filed May 27, 1924 Inventor John D. IILLLLcircL PILs Attorney Patented July 20, 1926.

UNITED STATES 1,593,405 PATENT OFFICE.

JOHN D. HILLIARD, 0F SCHENECTADY, NEW YORK, ASSIGNOR' TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

From-BREAK swrron.

Application filed May 27,

My invention relates to electric switches of the fluid break type and particularly to switches of this type which are of relatively large capacity and are adapted to control high potential circuits. One object of my invention is to provide a switch of this type characterized in general by a construe tion which shall be economical of manufacture, rugged, durable in service, and of such a nature as to avoid difficulties heretofore incident to the transportation of fluid break switches of large proportions. Another object of my invention is to provide a fluid break switch having means for reducing the condensation of moisture in the presence of the insulating liquid thereof due to atmospheric changes. A further object is to provide means for removing moisture from air taken into the switch and means for preventing an outward rush of. material from said switch through said moisture removing means.

My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the ap pended claims.

In the drawing, F ig. 1 is a vertical cross sectional view of a switch constructed in accordance with my invention; F ig. 2 is a similar view of a modification thereof, and

I Fig. 8 is a detail showing a modification of the air-drying apparatus illustrated in Fig. 2. i

Referring first to Fig. 1, the receptacle: 1 is of concrete which may. be constructed permanently at the location of the switch and is shown sunk nearly its whole depth in the ground. That portion. which pro.- jects above the ground is shown reinforced against explosive forces by the surrounding channel and tie bolt structure 2. The cover 3 which may be metallic and which may be in several sections where. the structure is large to facilitate its transportation closes the top of the concrete receptacle and serves to support the insulator bushings 4. carrying the stationary contacts 5-. The cover 3- also forms a guide for the switch operating rod 6 in the common and well known manner. The insulating liquid 7, which for example may be oil, is enclosed by an inner metallic tank or container 8 which in the drawing is shown having a reinforced rim comprising the angle iron 9. A gasket 10 is arranged concrete receptacle.

1924. Serial No. 716,279;

between the cover 3 and the angle iron. 9 which permits sealing the inner container. The side walls and bottom of the tank 8 are spaced from the corresponding parts of the. concrete receptacle and on the bottom of the latter is a series of structural steel memhers 12, for example channels placed back to back in pairs, upon which rest the inner tank 8. Tie rods 13 having tensioning. nuts 14 at the upper ends thereof extend between each two channels forming a pair whereby the cover and tank maybe securely clamped together to resist the internal pressures which may occur when the switch opens in response to an overload or short circuit. The remaining space between the receptacle 1 and tank 82 packed with subdivided material such. as sand or equivalent material so as to providev a solid backing for the tank. By reason of this construction the tank 8 may be made comparatively thin, and. if desired may also be transported from the place of manufacture in a disassembled condition and welded together at the permanent site of the switch. The chief: purpose of the tank 8 is to provide an impervious container for the insulating liquid 7 for it is well known that if an insulating liquid such as a mineral oil is allowed to come into contact with the concrete it will soak into it and greatly reduce its mechanical strength; Furthermore, the concrete is liable to crack and it. is almost. impossible to stop a leak in a cracked. concrete tank. Above the point at which the ground forms an outer abutment for the concrete. receptacle the structure 2 will effectively reinforce the receptacle against explosive forces within the tank. If occasion demands it, the tank 8 may be readily removed bodily from the The cover being removed together with the contact mechanism carried thereby the sand filling may. be washed. away into a sump by a stream of water and the. tank. lifted to the; surface;

the case of a switch like that. described above which is. at least partially buried in the ground, conditions are more favorable to the precipitation of moisture in the insulating fluid from the air entering the switch by reason of its breathing action than in the case of switches as commonly constructed where the entire structure is surrounded by the atmosphere. As is well known, the pres ence of a slight amount of moisture in the insulating liquid, particularly in the case of oil, greatly reduces its dielectric strength and in the construction disclosed herein I have sought to reduce the amount of water, if not to eliminate it entirely, which can be taken up by the insulating liquid. To reduce the precipitation of moisture from the space above the liquid level by sudden decreases in temperature brought about by atmospheric changes, I have provided a heat insulating lining 18 which as shown in Fig. 1 covers the inner surface of the cover 3, portions of the insulator bushings l which are exposed to the air and gas above the liquid, and the sides of the tank down to or slightly below the liquid level which, as indicated on the drawing, is also approximately the depth of the frost line. The lining 18 may be of any suitable heat insulating material, such for example as hair feltand may be retained in place by sheet metal 19 suitably secured as by welding to the part covered by the heat insulating material thereby keeping the material dry at all times. lVithin the side walls of the tank 8 is the usual insulation lining 20.

A further means which I have devised for preventing moisture from being taken up by the insulating liquid consists in remo ing moisture from the air which is taken into the switch tank as a result-of its breathing action. Vith the exception of the single opening provided by the pipe 22 and a normally closed pressure operated safety valve, not shown, the tank is sealed so that this pipe provides the only passage by which the outside air may enter the tank. The pipe 22 is shown connected at its opposite end with the top of the vessel 2-3. The bottom of this vessel is connected by the pipe 24 with the top of a second vessel preferably of lead through the top of which, also passes a pipe 26 also preferably of lead or provided with a lead or other suitable lining. This pipe 26 extends for some distance down into the vessel and is shown topped by a rain shield 27. Near the bottom of the vessel 25 is a perforated partition 28 above which is a quantity of suitable material such as asbestos 29. The lower portion of the vessel 25 is filled with sulphuric acid 30 which is soaked up by the asbestos. The vessel 23 contains aquantity of calcium oxide through which air in passing from vessel to the tank must pass. All of the air which passes into the switch tank in breathing must first pass through the vessel 25 in the presence of sulphuric acid which having a strong aflinity for water removes moisture from the air as it passes through. Any acid fumes taken up by the air in its passage through the vessel 25 are removed by the calcium oxide in the vessel 23 so that only dry air free from acid finally reaches the switch tank. To prevent the insulating liquid in the tank from being blown into (.ZEGlS 2-3 and 25 and contaminating them and to prevent the injurious effects of a rush of hot gases through the air-drying apparatus a pressure operated valve is provided in the switch tank at the mouth or the tube This shown as comprising a cylinder 32 having perforations 33 near the top and scured to the sheet metal covering 19. A piston 3a: to which is attached a weight 35 slides in the cylinder 82, the perforations 33 being arranged to be covered when the piston is at its upper limit of movement. A sudden increase in pressure in the switch tank lifts the piston 34; to its uppermost position, thus preventing the escape of gas and liquid through the tube 22. V/ hen the internal pressure subsides an amount suliicientto permit the piston to fall, the tank is again placed in communication with the outside atmosphere through the moisture removing apparatus.

The modification illustrated by Fig. 2 differs from that of Fig. 1 in that it is sunk to a greater depth or completely buried in the ground. The concrete receptacle 40, the cover 4:1, the tank 12 and associated parts including the heat insulating lining are all similar to the corresponding parts of the form shown by Fig. 1. By reason of the fact that the cover ll is covered by earth those parts which project above the cover, for example the insulator bushings, the stuliing box for the operating rod and the manhole casing are extended to reach above the surface of the earth. Tubular shields 123 are shown extending up from the cover 4L1 through which extend the elongated in sulator bushings 1% which are surrounded .vith heatinsulatingjackets 15 extending from beneath the surface of the insulating liquid within the switch to a point above the surface of the ground. Those portions of the bushings which pass through the shields 4L3 are shown protected by an additional layer a5 of heat insulating material. The stulling box 1-6 for the operating rod 47 is shown carried at the top of a tubular shield 18 extending from the cover to a point above the surface of the ground. The space between the rod 47 and the walls of the shield 18 is also filled with heat insulating material. In Fig. 2 the space between the concrete receptacle and the tank is somewhat less than in Fig. 1 and in this form also the sand filling is shown omitted although it may of course be used if desired.

By burying the switch deeper in the ground and entirely below the frost line as in Fig. 2, the variations in temperature of those parts upon which moisture in the space above the liquid may condense are lessened and the amount of moisture condensed in the switch is accordingly reduced. In Fig. 2 a different form of container for the sulphuric acid is illustrated. Here the container is shown having a series of shallow pans 51 holding the acid and having vided at their upper portions with holes 53 for the passage of air.

Vhile I have described certain embodiments of my invention, I do not wish to be limited to the particular forms shown and described as it will be apparent that many modifications therein may be made Without departing from the scope of my invention as set forth in the appended claims.

WVhat I claim as new and desire to'secure by Letters Patent Of the United States, is,-

1. A fluid break switch comprising a tank containing insulating liquid, a cover there for, relatively movable contacts in said liquid, there being a space between said cover w and the surtace of said liquid and means for reducing the condensation of moisture in said space due to variations in temperature, comprising a surrounding layer of heat insulating material.

2. A fluid break switch comprising a covered tank containing insulating liquid and relatively movable contacts immersed therein, said tank being sunk in the ground and having an air space between the cover thereof and the liquid therein, and a heat insulating lining for said cover.

3. A fluid break switch comprising a tank sunk in the ground and partially filled with insulating liquid, a cover for said tank, stationary and movable contacts in said liquid, insulator bushings extending through said cover and supporting said stationary contacts, and a layer of heat insulating mate rial on said cover and on those portions of said tank and said bushings which extend between the surface of said liquid and said cover.

4. A fluid break switch comprising a nonmetallic receptacle sunk in the ground and containing insulating liquid, relatively movable contacts immersed in the liquid, a cover for the receptacle, a metallic lining for the receptacle, and filling material between the receptacle and its lining.

5. A fluid break switch comprising a cement receptacle sunk in the ground, a cover therefor, a sheet metal tank in said receptacle, insulating liquid and relatively movable contacts in said tank, means for securing said cover to said tank, and a subdivided filling material between said tank and said receptacle.

6. A fluid break switch comprising a builtup non-metallic receptacle sunk in the ground and containing insulating liquid, relatively movable contacts immersed in the liquid, a metallic cover for the receptacle, a

metallic lining for the sides and bottom of the receptacle, and a sand filling between the lining and the receptacle.

7. In a fluid break switch comprising a closed tank containing insulated liquid sunk in theground and providing an air space above the surface of the liquid, means form ing an air passage between said space and the atmosphere, means for removing moisture from air passing through said passage, and means responsive to a predetermined pressure in said space for closing said passage.

In witness whereof, I have hereunto set my hand this 26th day of May, 1924:.

JOHN D. HILLIARD. 

